Flesh out the README

Author: foolip

README.md

@@ -2,6 +2,18 @@
 
 This project tracks organize developer signals (interest, needs, wants, frustrations) around web platform features. The work is done within the [W3C WebDX Community Group](https://www.w3.org/community/webdx/).
 
+Signals is defined broadly to allow for any available data about web developers to be considered, and typically fall into one of these categories:
+
+- Survey results, for example from [State of CSS](https://stateofcss.com/) or [MDN short surveys](https://github.com/web-platform-tests/interop/issues/245)
+- Developer interviews, such as those done for the [MDN Browser Compatibility Report 2020](https://mdn.dev/archives/insights/reports/mdn-browser-compatibility-report-2020.html)
+- Browser bugs, including upvote/star counts
+- Reactions on GitHub issues relating to web platform features
+- Blogs, podcasts, or social media
+
+To the extent possible, signals will be organized around [`web-features`](https://github.com/web-platform-dx/web-features).
+
+This project is only about organizing signals, not about conducting or coordinating research. For that, see the [WebDX research workstream](https://github.com/web-platform-dx/developer-research).
+
 ## Background
 
 A discussion on [organizing developer signals around features](https://github.com/web-platform-dx/developer-research/issues/31) led to the creation of this project, see that discussion for more background.